Multiple fnplot and different color

Hello! I'm a young geology student. I'm doing a thesis with matlab. I have to plot P-T-time path.

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(see the figure Vittoria.jpg). I have to plot of line just like that, but i'm not able to link to each line with a specific color (see figure Disfatta) I use fnplot associated to cscvn... what can i do?

This is my code

for i=1:num_points

    f=plot(markt(:,i),markp(:,i),'d');
    set(f,'Color',cmap(i,:));
     %if(i==1)
%        for j=1:num_cycle
%            text(markt(j,i),markp(j,i),num2str(timesum(j)),'HorizontalAlignment','left');
%        end
%      end
    a=makrt'
    b=markp'
    hold on

   fnplt(cscvn([a(i,:);b(i,:)]));

    hold off

      hold all
      h(i)=i;

end